The present invention relates to the use of an amine functional polymer as a rheology modifier for non-aqueous paints, inks, filled thermosetting resins, thermosetting resin-based gelcoats and to millbases, paints and inks, filled thermosetting resins and thermosetting based gelcoats containing said rheology modifier. The ink includes that used in either impact or non-impact printing, including drop-on-demand (DOD) printing.
Solvent based coatings have a tendency to xe2x80x9csagxe2x80x9d or run down when the coating is applied to inclined and particularly vertical surfaces. This is particularly true in the case of high solids coating formulations which are becoming increasing important with the need to reduce the Volatile Organic Compound (VOC) content of the coatings. There is thus a clear need for rheology modifying agents which reduce the tendency of coatings to sag. Ideally such rheology modifying agents should impart shear thinning properties on the coating such as high viscosity under low shear conditions to inhibit sag after application of the coating and low viscosity under high shear to permit flow and levelling of the coating during application.
Thermosetting resin based gelcoats, and filled thermosetting resins when used in spray and hand lay-up applications, also have a strong tendency to sag when applied to vertical surfaces. Typically this difficulty is addressed through the use of thixotropes such as fumed silicas, but their ultra-fine particulate state makes them difficult to handle in terms of both their ease of incorporation into formulations, and extremely dusty nature.
The relatively high density of most fillers used in thermosetting resins means that the said fillers may have a strong tendency to settle on storage, even for quite short periods of time, leaving an uneven distribution of filler between the different levels within the formulation, and even a dense sediment on the base of the container. This problem may be addressed by mechanical means (stirring or rolling the container), or by incorporation of an appropriate agent that will help the formulation to resist settling. Ideally such anti-settling agents should show shear thinning behaviour.
U.S. Pat. No. 3,979,441 discloses oil-soluble polymers of N-3-amino alkyl acrylamides such as N-(1,1-dimethyl-3-dimethylaminopropyl) acrylamide which are obtained by copolymerisation with a monomer such as an alkyl (meth)acrylate containing an alkyl group with at least 8 carbon atoms. The polymers are used as viscosity modifiers in lubricants but their use in paints is neither disclosed nor envisaged.
U.S. Pat. No. 5,312,863 discloses cationic latex coatings obtained by polymerising at least one ethylenically unsaturated monomer wherein at least one of the monomers contains a cationic functional group. Preferably, the concentration of the cationic functional monomer is from 0.5 to 15% by weight of the total polymerisable monomers used to prepare the cationic polymer, and more preferably from 1 to 5% by weight. There is no disclosure that such cationic polymers can be used as a rheology modifier (hereinafter xe2x80x9cRMxe2x80x9d) in non-aqueous based paints and inks.
More recently, U.S. Pat. No. 5,098,479 discloses a process for preparing a hydrocarbon-soluble thickener for zinc-containing metal resinate inks which comprises the reaction product of
a) up to 99% by weight of an alkyl or cycloalkyl ester of (meth) acrylic acid;
b) up to 98% by weight styrene;
c) 1 to 40% by weight of an amine-containing monomer;
d) up to 20% by weight of a carboxyl-containing monomer; and
e) a catalytic amount of a free-radical polymerisation initiator.
These thickeners have all been specifically developed for use with metal resinates in gravure printing inks and none of the specific thickeners are made using more than 15% by weight amine-containing monomers.
It has now been found that improved resistance against sag, running or settling can be obtained if the RM polymer contains not less than 42% by weight of the residue of an amine containing monomer.
According to the invention there is provided the use of an amine functional polymer, including salts thereof, as a rheology modifier for solvent-based paints, inks, filled thermosetting resins and thermosetting resin-based gelcoats, whereby the amine functional polymer contains not less than 42% by weight of the residue of one or more amine-containing monomers, or salts thereof, relative to the total weight of the polymer.
The amine functional polymer, including salts thereof, is referred to hereinafter as AFP.
Preferably, the AFP contains not less than 45% and more preferably not less than 50% by weight of the residue of an amine-containing monomer relative to the total weight of the polymer.
It is also preferred that the AFP contains not greater than 90% and more preferably not greater than 80% by weight of the residue of an amine-containing monomer relative to the total weight of the polymer.
The weight average molecular weight (Mw) of the AFP is preferably between 30,000 and 250,000, more preferably between 40,000 and 100,000 and especially between 65,000 and 85,000.
The AFP is preferably obtainable from two or more monomers which contain at least one, and preferably, only one ethylenically unsaturated group.
In one preferred class of AFP, the amine-containing monomer is a compound of formula 1 
wherein
R is hydrogen or C1-6-alkyl;
A is oxygen, sulphur, a group xe2x80x94COOxe2x80x94 or a group xe2x80x94CONR3xe2x80x94 wherein R3 is hydrogen or C1-12-alkyl;
X is C2-10-alkylene;
R1 and R2 is each, independently, hydrogen, hydroxyalkyl or C1-12-alkyl; or
R1 and R2 together with the nitrogen atom to which they are attached, form a ring.
When R is C1-6-alkyl, it is preferably C1-4-alkyl such as methyl.
When X is alkylene, it may be linear or branched. Preferably at least two carbon atoms of the alkylene group are in a chain connecting A with the nitrogen atom.
When R1 and/or R2 is hydroxyalkyl it is preferably hydroxy-C2-4-alkyl.
When R1 and R2 together with the nitrogen atom to which they are attached form a ring, the ring preferably contains 6 members such as morpholinyl, piperazinyl, pyridyl, pyrrolidinyl and N-alkylpiperidinyl such as Nxe2x80x94C1-18-alkyl- and especially Nxe2x80x94C1-6-alkyl piperidinyl.
Examples of the compounds of formula 1 are:
10-aminodecyl vinyl ether;
9-aminooctyl vinyl ether;
6-(diethylamino)hexyl (meth)acrylate;
2-(diethylamino)ethyl vinyl ether;
5-aminopentyl vinyl ether;
3-aminopropyl vinyl ether;
2-aminoethyl vinyl ether;
2-aminobutyl vinyl ether;
4-aminobutyl vinyl ether;
3-(dimethylamino)propyl (meth)acrylate;
2-(dimethylamino)ethyl vinyl ether;
N-(3,5,5-trimethylhexyl)aminoethyl vinyl ether;
N-cyclohexylaminoethyl vinyl ether;
3-(t-butylamino)propyl (meth)acrylate;
2-(1,1,3,3-tetramethylbutylamino)ethyl (meth)acrylate;
N-t-butylaminoethyl vinyl ether;
N-methylaminoethyl vinyl ether;
N-2-ethylhexylaminoethyl vinyl ether;
N-t-octylaminoethyl vinyl ether;
beta-morpholinoethyl (meth)acrylate;
4-(beta-acryloxyethyl) pyridine;
beta-pyrrolidinoethyl vinyl ether;
5-aminopentyl vinyl sulfide;
beta-hydroxyethylaminoethyl vinyl ether;
(N-beta-hydroxyethyl-N-methyl) aminoethyl vinyl ether;
hydroxyethyidimethyl (vinyloxyethyl) ammonium hydroxide;
2-(dimethylamino)ethyl (meth)acrylate;
2-(dimethylamino)ethyl (meth)acrylamide;
2-(t-butylamino)ethyl (meth)acrylate;
3-(dimethylamino)propyl (meth)acrylamide;
2-(diethylamino)ethyl (meth)acrylate;
2-(dimethylamino)ethyl (meth)acrylamide.
In a further preferred class of AFP, the amine containing monomer is a compound of formula 2 
wherein
R4 is hydrogen or C1-12-alkyl; and
n is from 1 to 4.
Examples of amine functional monomers of formula 2 are 4-vinylpyridine, 2,6-diethyl-4-vinylpyridine, 3-dodecyl-4-vinylpyridine and 2,3,5,6-tetramethyl-4-vinylpyridine.
The quaternised form of weak base functional monomers such as those weak base functional monomers which have been reacted with alkyl halides, such as benzyl chloride and ethyl bromide or with epoxides such as ethyleneoxide and propyleneoxide, or with dialkylsulphate such as dimethylsulphate, can also be used. These monomers containing quaternary ammonium functional groups are also regarded as amine-functional monomers for the purpose of this invention.
In addition to the amine-containing monomer, the AFP may also contain the residue of one or more nonionic mono-ethylenically unsaturated monomers. Examples of such monomers are styrene, alpha-methyl styrene, vinyl toluene, vinyl naphthalene, ethylene, vinyl acetate, vinyl versatate, vinyl chloride, vinylidene chloride, acrylonitrile, meth-acrylonitrile, (meth)acrylamide, various (C1-C20)alkyl and (C3-C20)alkenyl esters of (meth)acrylic acid; for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl(meth)acrylate, isobutyl(meth)acrylate, 2-ethyl-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, tetradecyl (meth)acrylate, n-amyl (meth)acrylate, neopentyl (meth)acrylate, cyclopentyl (meth)acrylate, lauryl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate; other (meth)acrylates such as isobornyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, 2-bromoethyl (meth)acrylate, 2-phenylethyl (meth)acrylate, and 1-naphthyl (meth)acrylate; alkoxylalkyl (meth)acrylates such as ethoxyethyl (meth)acrylate; and dialkyl esters of ethylenically unsaturated di- and tricar-boxylic acids and anhydrides, such as diethyl maleate, dimethyl fumarate, trimethyl aconitate, and ethyl methyl itaconate.
The AFP may also contain the residue of one or more multi-ethylenically unsaturated monomers. The amount of multi-ethylenically unsaturated monomer is controlled in order not to produce a gel in preparation of the AFP. Examples of such monomers are allyl (meth)acrylate, tripropyleneglycol di(meth)acrylate, diethyleneglycol di(meth)acrylate, ethyleneglycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,3-butyleneglycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, diallylphthalate, trimethylolpropane tri(meth)acrylate, divinyl benzene, divinyl toluene, trivinyl benzene and divinyl naphthalene. The amount of multi-ethylenically unsaturated monomer is preferably less than 5%, more preferably less than 2% based on the total weight of monomers used to prepare the AFP.
Monomers containing functional groups which may be available for further reaction after synthesis of the AFP may also be included. Examples of such functional groups are hydroxy, carboxy and fatty acid. Examples of these functional monomers are 2-hydroxyethyl (meth)acrylate and (meth)acrylic acid.
The functional groups in the AFP derived from the functional monomers may be utilised to incorporate the AFP into the crosslinked matrix of a thermosetting or air drying coating composition. An example of this is where the AFP contains hydroxy functionality. Such an AFP may be incorporated into the crosslinked matrix of a hydroxy functional film-forming binder resin by use of a suitable crosslinking agent such as a polyisocyanate or melamine formaldehyde derivative in the coating composition. When the AFP contains the residue of a carboxy functional monomer the amount of such monomer is preferably less than 3% and especially less than 1% by weight based on the total weight of monomers.
The polymerisation conditions to produce the AFP should be selected to minimise reaction, if any, between the amine functional group and the post-polymerisation crosslinkable functional group. After polymerisation an appropriate multi-functional crosslinking agent can be reacted with crosslinkable functional groups pendant from the polymer chain. Alternatively, the amine functional group itself can serve as crosslinking site.
Some of the AFP""s according to the invention are novel. Thus, according to a further aspect of the invention there is provided an amine-functional polymer (AFP) which comprises not less than 42% by weight of the AFP of a residue of an amine-containing monomer having an ethylenically unsaturated group and a residue of styrene, including salts thereof.
Preferably, the AFP further comprises the residue of an ethylenically unsaturated monomer which contains a hydroxyl group.
As a further aspect of the invention there is provided an AFP which comprises not less than 42% by weight of the AFP of an amine-containing monomer having an ethylenically unsaturated group and a residue of a C1-6-alkyl (meth)acrylate, including salts thereof.
Useful AFP""s have been prepared from styrene and 2-dimethylaminoethylmethacrylate (hereinafter DMAEMA) optionally containing up to 10% 2-hydroxyethylmethacrylate.
The AFP""s used as rheology modifiers according to the present invention may be prepared by any method known to the art. However, it is preferred that the AFP is prepared by a solvent polymerisation process and that the solvent is selected for compatibility with the end-use paint or ink with which the AFP is to be used. The AFP may also be prepared by a standard batchwise process or by continuous feed of the monomers.
As a further variant, the AFP may be prepared by amine functionalisation of a preformed polymer which is substantially devoid of amine and/or cationic groups. However, it is much preferred that the AFP is prepared from two or more monomers, at least one of which is an amine-containing monomer.
As disclosed hereinbefore, the AFP is primarily of use as a RM in paints, inks, gelcoats and filled thermosetting resins but may also be used in any non-aqueous coating system which it is desired to thicken. Thus, the AFP may be part of a clear coating comprising a film-forming binder resin and an organic liquid which may optionally contain a particulate solid such as a pigment and optionally a dispersant to disperse the particulate solid when the binder resin does not act as dispersant.
According to a further aspect of the invention there is provided a composition comprising the AFP, organic liquid and a film-forming binder resin. The binder resin system may be that found typically in conventional coatings as well as high solids coatings. Illustrative examples are binders such as those based on alkyds, polyester-melamine, polyester-urea/formaldehyde, alkyd-melamine, alkyd-urea/formaldehyde, acrylic-melamine, acrylic-urea/formaldehyde, epoxy resins, epoxy ester-melamine, polyurethane resins, acrylic resins, oleoresins, unsaturated polyesters, polyvinyl acetates, polyvinyl chlorides or vinyl acrylics. The preferred resins comprise alkyds, polyester-melamine, polyester-urea/formaldehyde, alkyd-melamine, acrylic melamine or polyurethanes. The most preferred resins comprise polyester-melamine, acrylic-melamine or polyurethanes. Preferably, the binder resin is other than a metal resinate.
As a still further aspect of the invention there is provided a millbase, paint, ink or thermosetting resin-based gelcoat comprising the AFP, organic liquid and/or reactive monomer, particulate solid and a film-forming binder resin or a thermosetting resin. It is also preferred that the millbase, paint, ink or thermosetting resin-based gelcoat further comprises a dispersant to uniformly distribute the particulate solid throughout the organic liquid.
Preferably, the particulate solid is a pigment.
A further aspect of the invention provides a composition comprising the AFP, a thermosetting resin and optionally a reactive monomer. The resin may be that typically found in the thermosetting resin systems. Illustrative examples of such resins include unsaturated polyesters, poly(meth)acrylates, urethanes, urethane-acrylates, epoxy resins, vinyl esters, allyl resins, silicone resins, amino resins, phenolics, melamine formaldehydes and urea formaldehydes. Examples of reactive monomers include styrene and methyl methacrylate.
As a further aspect of the invention there is provided a filled thermosetting resin based composite comprising the AFP, a thermosetting resin system, a particulate solid material and optionally a reactive monomer. Preferably, the particulate solid material is wholly or mainly filler.
The organic liquid is preferably a polar organic medium or a substantially non-polar aromatic hydrocarbon, aliphatic hydrocarbon or halogenated hydrocarbon. By the term xe2x80x9cpolarxe2x80x9d in relation to the organic medium is meant an organic liquid or resin capable of forming moderate to strong bonds as described in the article entitled xe2x80x9cA Three Dimensional Approach to Solubilityxe2x80x9d by Crowley et al in Journal of Paint Technology, Vol. 38, 1966, at page 269. Such organic media generally have a hydrogen bonding number of 5 or more as defined in the abovementioned article.
Examples of suitable polar organic liquids are amines, ethers, especially lower alkyl ethers, organic acids, esters, ketones, glycols, alcohols and amides. Numerous specific examples of such moderately strongly hydrogen bonding liquids are given in the book entitled xe2x80x9cCompatibility and Solubilityxe2x80x9d by Ibert Mellan (published in 1968 by Noyes Development Corporation) in Table 2.14 on pages 39-40 and these liquids all fall within the scope of the term polar organic liquid as used herein.
Preferred polar organic liquids are dialkyl ketones, alkyl esters of alkane carboxylic acids and alkanols, especially such liquids containing up to, and including, a total of 6 carbon atoms. As examples of the preferred and especially preferred liquids there may be mentioned dialkyl and cycloalkyl ketones, such as acetone, methyl ethyl ketone, diethyl ketone, di-isopropyl ketone, methyl isobutyl ketone, di-isobutyl ketone, methyl isoamyl ketone, methyl n-amyl ketone and cyclohexanone; alkyl esters such as methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate, ethyl formate, methyl propionate, methoxy propylacetate and ethyl butyrate; glycols and glycol esters and ethers, such as ethyl glycol, 2-ethoxyethanol, 3-methoxypropylpropanol, 3-ethoxypropylpropanol, 2-ethoxyethyl acetate; alkanols such as methanol, ethanol, n-propanol, isopropanol, n-butanol and isobutanol and dialkyl and cyclic ethers such as diethyl ether and tetrahydrofuran.
The substantially non-polar, organic liquids which may be used, either alone or in admixture with the aforementioned polar solvents, are aromatic hydrocarbons, such as toluene and xylene, aliphatic hydrocarbons such as hexane, heptane, octane, decane, petrolium distillates such as white spirit, mineral oils, vegetable oils and halogenated aliphatic and aromatic hydrocarbons, such as trichloro-ethylene, perchloroethylene and chlorobenzene.
The particulate solid may be any inorganic or organic solid material which is substantially insoluble in the organic liquid at the temperature concerned and which it is desired to stabilise in a finely divided form therein.
Examples of suitable solids are pigments for solvent inks; pigments, extenders and fillers for paints and plastics materials; particulate ceramic materials; magnetic materials and magnetic recording media, fire retardants such as those used in plastics materials and biocides, agrochemicals and pharmaceuticals which are applied as dispersions in organic media.
A preferred solid is a pigment from any of the recognised classes of pigments described, for example, in the Third Edition of the Colour Index (1971) and subsequent revisions of, and supplements thereto, under the chapter headed xe2x80x9cPigmentsxe2x80x9d. Examples of inorganic pigments are titanium dioxide, zinc oxide, Prussian blue, cadmium sulphide, iron oxides, vermillion, ultramarine and the chrome pigments, including chromates, molybdates and mixed chromates and sulphates of lead, zinc, barium, calcium and mixtures and modifications thereof which are commercially available as greenish-yellow to red pigments under the names primrose, lemon, middle, orange, scarlet and red chromes. Examples of organic pigments are those from the azo, disazo, condensed azo, thioindigo, indanthrone, isoindanthrone, anthanthrone, anthraquinone, isodibenzanthrone, triphendioxazine, quinacridone and phthalocyanine series, especially copper phthalocyanine and its nuclear halogenated derivatives, and also lakes of acid, basic and mordant dyes. Carbon black, although strictly inorganic, behaves more like an organic pigment in its dispersing properties. Preferred organic pigments are phthalocyanines, especially copper phthalocyanines, monoazos, disazos, indanthrones, anthranthrones, quinacridones and carbon blacks.
Other preferred solids are: extenders and fillers such as calcium carbonate, alumina, alumina trihydrate (ATH), sand, china clay, talc, kaolin, silica, barytes and chalk; particulate ceramic materials such as alumina, silica, zirconia, titania, silicon nitride, boron nitride, silicon carbide, boron carbide, mixed silicon-aluminium nitrides and metal titanates; particulate magnetic materials such as the magnetic oxides of transition metals, especially iron and chromium, e.g. gamma-Fe2O3, Fe3O4, and cobalt-doped iron oxides, calcium oxide, ferrites, especially barium ferrites; and metal particles, especially metallic iron, nickel, cobalt and alloys thereof; agrochemicals such as the fungicides flutriafen, carbendazim, chlorothalonil and mancozeb and fire retardants such as aluminium trihydrate and magnesium hydroxide.
The dispersant is preferably a polyesteramine or polyester ammonium salt and is particularly the condensation product of a polyester and an amine, polyamine or polyimine, including salts thereof. Examples of suitable dispersants are those disclosed in GB 1,373,660, GB 2,001,083, EP 158,406, EP 690,745, WO 98/19784 and WO 99/49963.
The millbase, paint, ink, thermosetting resin or thermosetting resin-based gelcoat may also contain other adjuvants such as fluidising agents, anti-sedimentation agents, plasticisers, levelling agents and preservatives. Preferred fluidising agents are those disclosed in GB 1,508,576, GB 2,108,143 and WO 01/14479.
As disclosed hereinbefore, the use of the AFP according to the invention exhibit advantage over those disclosed in U.S. Pat. No. 5,098,479. They exhibit superior anti-sag characteristics and exhibit no significant deleterious effects on other properties of the paint or ink such as gloss, haze and drying rates. The use of AFP according to the invention will also reduce settling and sedimentation of fillers and other particulate materials in filled thermosetting resins and thermosetting resin based gelcoats.
The amount of AFP in the paint, ink, filled thermosetting resin or thermosetting resin-based gelcoat, is preferably from 0.01% to 5.0%, more preferably from 0.1 to 1.0% and especially from 0.1 to 0.5% by weight based on the total weight of the paint or ink.
When the paint, ink, millbase, filled thermosetting resin or thermosetting resin-based gelcoat contains a resin which is substantially free from anionic groups it has been found that improved anti-sag and anti-settling properties are obtained by adding an organic compound containing two or more anionic groups (hereinafter OCA) to the paint, ink, millbase, filled thermosetting resin or thermosetting resin-based gelcoat. The improvement in anti-sag and anti-settling properties is particularly noted where the particulate solid contains substantially no anionic character or anionic surface coating and especially where the resin is substantially free from anionic groups.
The OCA may contain sulphate, sulphonate, phosphonate or especially phosphate groups. Preferably, the weight-average molecular weight of the OCA is not greater than 10,000, more preferably not greater than 5000 and especially not greater than 2000. It is also preferred that the number of anionic groups is not greater than four.
Preferred OCA""s are substantially colourless (i.e. free from chromophoric groups) and are particularly alkoxylates, especially those derived from polytetrahydrofuran, butylene oxide, propylene oxide and especially ethylene oxide, including mixtures thereof.
It is particularly preferred that the OCA exhibits dispersant properties. Examples of such OCA""s are the phosphate esters disclosed in WO 97/42252 and WO 95/34593.
The amount of OCA in the paint, ink, millbase, filled thermosetting resin or thermosetting resin-based gelcoat may be varied over a wide range but is preferably such that the number of anionic groups of the OCA does not exceed the number of basic groups of the AFP. Preferably the amount of OCA is such that the number of anionic groups of the OCA is not greater than 60%, more preferably not greater than 40% and especially not greater than 20% of the number of basic groups of the AFP.
The invention is now described in further detail in the following non-limiting examples wherein all references are to parts by weight unless expressed to the contrary.